In nearly every sector of the electronics industry, electronic circuitry involves the interconnection of an integrated chip (hereinafter “chip”) and a surface or device upon which the chip is supported. During operation of the circuitry, heat is generated and a heat flux is established between the chip and its environment. In order to remove heat more effectively to ensure the proper functioning of the circuitry, the heat flux is disseminated across a surface area larger than the surface area of the chip and transferred to an attached heat sink device. Once the heat is transferred to the heat sink device, it can be removed by a forced convection of air or other cooling means.
In some applications, multiple processors and their associated control and support circuitry are arranged on a single chip. Such arrangements may result not only in a further increase in the heat flux, but also in a non-uniform distribution of the heat flux across the surface of the chip. The non-uniformity of the distribution of the heat flux is generally such that a higher heat flux is realized in the processor core region and a significantly lower heat flux is realized in the region of the chip at which the control and support circuitry is disposed. The high heat flux in the processor core region may cause devices in this region to exceed their allowable operating temperatures. The resulting disparity in temperature between the two regions, which may be significant, may contribute to the stressing and fatigue of the chip.
A thermally conductive heat spreading device is oftentimes disposed between the chip and the heat sink device to facilitate the dissemination of heat from the chip. Such heat spreading devices are generally plate-like in structure and homogenous in composition and fabricated from materials such as copper, aluminum nitride, or silicon carbide. Newer carbon fiber composites exhibit even higher thermal conductivities than these traditional thermal spreader materials; however, they tend to be anisotropic in nature, exhibiting wide variations in thermal conductivity between a major axis normal to the face of the structure (in the Z direction) and the axes orthogonal to the major axis (in the X and Y directions). Moreover, the lower thermal conductivity in the direction along the major axis tends to have the effect of increasing the thermal resistance of the heat spreading device, thereby inhibiting the dissemination of heat from the device.